Debt - Additional Information (Detail)			3 Months Ended		6 Months Ended
	May. 30, 2014 USD ($) promissory_note	Oct. 01, 2009 USD ($) Promissory_Notes	Jun. 30, 2015 USD ($) property	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) property ExtensionOptions	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	Oct. 31, 2009 promissory_note
Line of Credit Facility [Line Items]
Debt outstanding			$ 391,900,000		$ 391,900,000		$ 358,200,000
Proceeds from the issuance of senior unsecured notes payable					0	$ 260,000,000
Secured revolving credit facility			35,000,000		35,000,000		0
Mortgage notes payable			96,854,000		96,854,000		98,205,000
Interest expense			5,989,000	$ 6,452,000	11,890,000	9,779,000
Amortization of deferred financing costs			600,000	300,000	1,100,000	500,000
Amortization of debt discount				$ 20,000		$ 51,000
Interest payable			1,700,000		1,700,000		$ 1,700,000
Johnson Land Enterprises, LLC [Member] | Promissory Notes September 30, 2019 [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount		$ 10,000,000.0
Mortgage notes payable			$ 500,000		$ 500,000
Number of promissory notes | promissory_note								4
Number of promissory notes repaid | promissory_note	3
Number of promissory notes | Promissory_Notes		4,000,000
Interest rate			6.00%		6.00%
Ensign [Member]
Line of Credit Facility [Line Items]
Debt outstanding			$ 359,512,000		$ 359,512,000
General Electric Capital Corporation [Member]
Line of Credit Facility [Line Items]
Advances included in mortgage note payable					49,500,000
General Electric Capital Corporation [Member] | Mortgage Notes Payable due May 30, 2017 [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount			$ 46,900,000		$ 46,900,000
Debt instrument, maturity date					May 30, 2017
Number of properties subject to mortgage loans | property			10		10
Mortgage notes payable			$ 96,400,000		$ 96,400,000
Advances included in mortgage note payable	$ 50,700,000
Debt instrument payment amortization period					25 years
Debt instrument blended interest rate					7.25%
Debt instrument, number of extension options | ExtensionOptions					2
Debt instrument, extension options period					12 months
Extension fees equal percent on outstanding principal balance			0.25%		0.25%
Debt Instrument, Notice Period For Prepayments Without Penalty					30 days
Debt instrument interest rate , terms					This advance bears interest at a floating rate equal to three month LIBOR plus 3.35%, reset monthly and subject to a LIBOR floor of 0.50%, with monthly principal and interest payments based on a 25 year amortization.
General Electric Capital Corporation [Member] | Mortgage Notes Payable due May 30, 2017 [Member] | Floor [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread					0.50%
General Electric Capital Corporation [Member] | Mortgage Notes Payable due May 30, 2017 [Member] | Floating Rate [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread					3.35%
Senior Unsecured Notes [Member]
Line of Credit Facility [Line Items]
Debt instrument, face amount	$ 260,000,000.0
Debt instrument, interest rate	5.875%		5.875%		5.875%
Proceeds from the issuance of senior unsecured notes payable	$ 260,000,000
Net proceeds from issuance of notes	$ 253,000,000
Debt instrument, maturity date					Jun. 01, 2021
Frequency of interest payable on notes					Interest on the Notes is payable on June 1 and December 1 of each year, beginning on December 1, 2014.
Debt instrument, early redeemable date					Jun. 01, 2017
Debt instrument, redemption price, percentage	100.00%
Debt instrument, redemption price, percentage upon change of control	101.00%
Senior Unsecured Notes [Member] | Ensign [Member]
Line of Credit Facility [Line Items]
Approximate amount transferred from net proceeds	$ 220,800,000
Senior Unsecured Notes [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Redeemable percentage of aggregate principal amount of notes	35.00%
Senior Unsecured Notes [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Percentage of aggregate principal amount of notes outstanding	65.00%
Senior Secured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, borrowing capacity	$ 150,000,000.0
Line of credit facility, additional borrowing capacity	$ 75,000,000.0
Line of credit facility, maturity date					May 30, 2018
Line of credit facility, extension period					1 year
Secured revolving credit facility			$ 35,000,000		$ 35,000,000
Line of credit facility, commitment fee			$ 200,000		$ 400,000
Senior Secured Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread	1.00%
Debt instrument, interest rate effective percentage rate minimum	2.00%
Debt instrument, interest rate effective percentage rate maximum	2.50%
Senior Secured Revolving Credit Facility [Member] | Floor [Member]
Line of Credit Facility [Line Items]
Debt instrument, interest rate effective percentage rate minimum	1.00%
Debt instrument, interest rate effective percentage rate maximum	1.50%
Senior Secured Revolving Credit Facility [Member] | Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread	0.50%
Senior Secured Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Line of credit facility, commitment fee percentage	0.50%
Senior Secured Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Line of credit facility, commitment fee percentage	0.35%